Three landowners on the site of a proposed D.C. baseball stadium filed suit in federal court yesterday, alleging that the District government is violating their civil rights by illegally attempting to seize their properties.

The lawsuit, brought by homeowner Kenneth B. Wyban and two investment partnerships, states that city officials conducted a faulty study to determine the cost of privately held land at the site along the Anacostia River waterfront in Southeast Washington.

Under city law, the stadium cannot be built if the cost of the 14 acres, stadium infrastructure and environmental remediation exceeds $165 million, a cap established by the D.C. Council. The study cited in the lawsuit, conducted by Chief Financial Officer Natwar M. Gandhi, estimated the cost of those three elements at $161.4 million.

The lawsuit calls Gandhi's report "arbitrary, capricious, and inconsistent with law, unsupported by the record, and indefensible" and asks the court to issue an injunction against any action by the city to seize the land.

Barry M. Hartman, an attorney for the plaintiffs, declined to comment on the lawsuit yesterday.

Traci Hughes, spokeswoman for the D.C. attorney general's office, said the city is aware of the lawsuit, but she declined to address the specifics.

The District government is attempting to acquire 14 acres from the 33 individuals or conglomerates that own them. City officials are analyzing the properties to develop bids for the land, starting in mid-August, said Carol Mitten, director of the city's Office of Property Management.

The city hopes to have control of the land by the end of the year in order to complete the $535 million stadium project for the Washington Nationals by March 2008. If the city cannot buy the land, it will seize it through eminent domain, officials have said.

This is the third lawsuit filed by owners of property on the stadium site. One, which alleges that the city denied expansion permits to a trash transfer station to keep the company's value low, is pending. A second that challenged Gandhi's study was dismissed by a Superior Court judge who ruled that no injunction was necessary because the city had not begun eminent domain proceedings.

Vince Morris, spokesman for Mayor Anthony A. Williams (D), declined to discuss the specifics of the most recent lawsuit. But he said the mayor is not worried that the lawsuits will set back the stadium's construction timetable.

"We wish people wouldn't file lawsuits," Morris said. "But we'll just work to overcome that."

The three landowners who filed yesterday's lawsuit own markedly different plots. Wyban lives in his five-bedroom house and said he had been planning to turn it into a bed-and-breakfast. He said he halted his plans because he was unsure whether he could remain at the site. Gandhi estimated his property to be worth $696,000.

Southeast Land Development Associates owns a 67,000-square-foot parking lot that is used for Metro buses. Gandhi estimated its value at $9 million. And Square 706 LLC owns 3,233 square feet of vacant land that Gandhi pegged at $298,213.

Mitten's office has sent letters to the landowners saying that all owners must vacate their properties by year's end.

The lawsuit states that because of action from the city, the plaintiffs "can no longer use their property as they have intended, can no longer accept other offers to purchase their property, and are being forced into an illegal process that will culminate in the seizure of their property."